There are many situations where is it desirable to locate buried utilities such as pipes and cables. For example, before starting any new construction that involves excavation, worker safety and project economic concerns require the precise location and identification of existing underground utilities such as underground power lines, gas lines, phone lines, fiber optic cable conduits, cable television (CATV) cables, sprinkler control wiring, water pipes, sewer pipes, etc., collectively and individually herein referred to as “buried objects.”
Locating transmitters and receivers used in buried object locating systems, as well as locating methods using such systems, are known in the art. For example, some locating transmitters generate and transmit a current output signal to a buried object, and a corresponding locating receiver detects a resulting signal radiated from the buried object to determine location. However, conventional locating transmitters and receivers typically operate on a single frequency for signal transmission and detection. Depending on the nature of the operation, restriction to a single frequency may provide unsatisfactory results. For example, in systems which transmit and detect only a single frequency, it is difficult for an operator to determine if the current signal is the signal of interest, or a jamming or interfering signal. Additionally, certain output frequencies may be better suited than others in a given locating operation.
Thus, various multi-frequency transmitters have been developed to overcome problems arising from this constraint. However, while existing multi-frequency transmitters are capable of generating multiple current signals at different frequencies, such transmitters are not optimized for the current output to be sensed, processed, and displayed by a receiver on multiple frequencies at the same time. Thus, the operator is responsible for selecting the appropriate frequency signal for the specified locating operation and the information obtained is a function of only a single frequency at a particular time. Accordingly, there is a need in the art to address the above-described, as well as other problems.